HIV -1 infection is associated with progressive and ultimately profound immunosuppression, resulting in the development of opportunistic infections and neoplasms in the later stages of illness. A hallmark of HIV-1 infection is the characteristic progressive decline in CD4 lymphocyte number and function that occurs over the course of illness. Because CD4 cells are central to the proper functioning of a myriad of immune responses, loss or dysfunction of these cells is thought to be a key component contributing to immunodeficiency. Therapeutic trials with antiretroviral agents have resulted in transient and relatively short- lived boosts in CD4 number, and ex vivo expansion of these cells has not been possible because stimulation and proliferation of CD4 cells results in activation of HIV-1 replication. Strategies to protect CD4 cells for ex vivo expansion and development of techniques to expand these cells to large numbers should facilitate not only adoptive therapy trials of these cells, but would also provide a source of CD4 cells for genetic manipulation. In preliminary studies in our laboratory, we have devised a strategy which enables the ex vivo expansion of CD4 lymphocytes from seropositive persons in the absence of ongoing viral replication. PBMC are expanded in the presence of a bispecific monoclonal antibody which results in the selective polyclonal expansion of CD4 lymphocytes, which can be successfully protected from ongoing viral replication by the addition of combination antiretroviral therapies during the ex vivo expansion. In a number of infected persons, CD4 lymphocytes have been expanded greater than 10(5)-fold, which would permit expansion to 10 (11) cells starting with only a few million cells. The resultant cultures are negative for active infection as evidenced by lack of HIV-1 p 24 antigen detection and inability to detect virus by coculture. We now propose to expand upon these preliminary studies with the ultimate aim of adoptive therapy with ex vivo-expanded CD4 cells in infected persons. We also propose to adapt these studies to the rhesus macaque animal model in order to experimentally address critical questions regarding adoptive cell therapy of viral infections, including trafficking and longevity of adoptively transferred cells. Specifically, we propose to a) Expand CD4-positive lymphocytes from infected persons ex vivo in the absence of ongoing viral replication and characterize the immunologic function of the expanded cells; b) Enrich for populations of CD4+ T lymphocytes reactive against defined antigens (HIV and other infectious agents) from infected persons; c) Protect expanded CD4 cells from HIV-1 infection by genetic manipulations using adenovirus-associated and retroviral vectors; d) Perform adoptive immunotherapy of similarly expanded and genetically modified CD4+T lymphocytes in rhesus macaques for cellular distribution, cell survival kinetics, and immune function assessment. These studies will lay the foundation for adoptive therapy using ex vivo expanded CD4 cells as a therapy for HIV-1 infection, and will pave the way for the use of autologous CD4 cells as a vehicle for gene therapy in this infection.